Commentators, almost always from the right, have documented liberal media bias for many years now. And the response by the perpetrators of this bias has been both constant and predictable: Circle the wagons and blame the accusers. Accuse us of bias for seeing their bias.

The bias we've been talking and writing about is usually about partisan politics and hot social issues like abortion. But there's one kind of liberal media bias that hasn't gotten much attention. It's a bias that liberals both in and out of the media often attach to conservatives, but almost never to themselves. It's racial bias.

My friend Lee Habeeb, a conservative radio executive who appears on cable TV from time to time, has written a piece in Newsweek about how too many journalists have played down -- and often downright ignored -- the murder of young black men in places like Chicago.

"In Chicago, it's Parkland every week," Habeeb writes about a city that had more than 1,400 homicides in 2016 and 2017. And in just the first week of May 2018, 84 people were shot -- nine of them wound up dead.

Journalists, of course, care very much about young black men who are shot -- when the person doing the shooting is a cop. Then, news organizations, even those based a thousand miles away, report the names of the dead -- like Michael Brown who was killed by a police officer in Ferguson, Missouri -- and (rightly) give as much information as possible about their deaths.

"But Americans know none of the thousands of innocent young black men and women killed by other black men in our nation's third largest city -- and across America," writes Habeeb. "There's a reason. A young black male's life is not worth reporting when it is taken by another black male. That's the real racism that prevails in America's newsrooms. The marginalization of black urban life."

Habeeb believes that liberal journalists don't like the storyline. "Journalists and activists can't blame the deaths on assault style weapons like the AR-15. Or the National Rifle Association."

It's true. Black on black murder doesn't fit the liberal journalists' template -- and not only because assault weapons aren't involved. Liberals journalists don't feel comfortable when it comes to reporting dysfunction in black neighborhoods in places like Chicago. If white kids in tony suburbs were being gunned down in such horrific numbers, you can be sure that the liberal media would more than simply take note. They'd run stories on Page 1 for days on end.

Does that mean that liberals think white lives matter more than black lives? It's not that simple -- not when you introduce paternalism and white liberal guilt into the mix.

When it comes to the slaughter of black young men, liberal journalists fear that playing up this kind of bad news could give ammunition to bigots, who might use the information to bolster their already nasty opinions of African-Americans.

And since much of the killing is the work of fatherless young men, that's another important story the national media would rather play down, and for the same reason. More dysfunction amounts to more ammo for the bigots.

"About 20,000 people live in my hometown of Oxford, Mississippi," Habeeb says, "and there are probably as many guns. But I can't remember the last murder spree in the local paper. That's because my town has lots of guns, but lots of fathers, too."

Too many on the left, whether they're in the media or not, worry about their "good racial manners," a term that Shelby Steele, a black conservative scholar came up with.

And it would be anything but good racial manners to give black on black murders the space the story deserves in the national media. Playing down uncomfortable truths about crime and dysfunction in places like Chicago is how liberal journalists show how decent they are, how protective of black people they are. But mostly, it makes them feel noble -- about themselves.